Refrigeration system with combination capacity and compressor overload control

ABSTRACT

A refrigeration system, and more particularly one having means for controlling against compressor overload and excess system capacity, comprising a compressor means, a condenser means connected at the output of the compressor means for condensing refrigerant discharged from the compressor means. An expansion device is connected between the output of the condenser means and the input of an evaporator means. A vortex amplifier is connected between the output of the evaporator means and the input of the compressor means, the amplifier having a main inlet and an outlet through which the refrigerant passes from the evaporator means to the compressor means, and a control inlet connected to a source of control fluid. Means are provided for varying discharge of the control fluid to the control input of the vortex amplifier in response to variations in compressor load from a prescribed load value, and to variations in system capacity from a prescribed capacity value.

United States Patent Porter 145-1 Apr. 30, 1974 REFRIGERATION SYSTEM WITH COMBINATION CAPACITY AND COMPRESSOR OVERLOAD CONTROL [75] Inventor: Maxson A. Porter, Springfield, Mo.

[73] Assignee: Paul Mueller Company, Springfield,

22 Filed: Dec; 1, 1971 21 Appl. No; 203,680

Primary ExaminerMeyer Perlin Attorney Agent, 0r Firm-Rogers, Ezell & Eilers ABSTRACT A refrigeration system, and more particularly one having means for controlling against compressor overload and excess system capacity, comprising a compressor means, a condenser means connected at the output of the compressor means for condensing refrigerant discharged from the compressor means. An expansion device is connected between the output of the condenser means and the input of an evaporator means. A vortex amplifier is connected between the output of the evaporator means and the input of the compressor means, the amplifier having a main inlet and an outlet through which the refrigerant passes from the evaporator means to the compressor means, and a control inlet connected to a source of control fluid. Means are provided for varying discharge of the control fluid to the control input of the vortex amplifier in response to variations in compressor load from a prescribed load value, and to variations in system capacity from a prescribed capacity value.

7 Claims, 4 Drawing Figures C0 lvpmsssoe 42 co NOE N5 ER 22 24 Q a PA N5 IQQJ) clay/g CAPACITY AND COMPRESSOR OVERLOAD CONTROL SUMMARY OF THE INVENTION This invention relates to a refrigeration system, and more particularly to one having means for controlling ity.

The control means includes a vortex amplifier which is a fluidic device of the type described and shown-in FIG. 3 of US. Pat. No. 3,369,374. In that patent such a device is shown as used in a refrigeration system for the single purpose of controlling the capacity of the system. This invention is an improvement' over the abovereferenced patent in using such a device for the dual purpose of reducing the capacity of the system when full capacity is undesirable and of preventing compressor overload.

Other patents ofinterest are US. Pat. Nos. 3,367,130 and 3,264,837 which describe an expansion valve and refrigeration system responsive to subcooling temperature. With subcooling valves of that type, compressor overload control cannot be built-in as with some conventional expansion devices. This invention, therefore, represents a substantial improvement over those systems using subcooling valves by providing them with such control. a

The system'of this invention generally includesa compressor means, a condenser means connected at the output of the compressor means for condensing refrigerant discharged from the compressor means. An expansion device is connected between the output of the condenser means and the input of an evaporator means.

The capacity and compressor overload control includes a vortex amplifier connected between the output of the evaporator and the input of the compressor means. The vortex amplifier has a main inlet and an outlet through which refrigerant passes from the evaporator means to the compressor means, and a control inlet connected to a source of control fluid. Means are provided for varyingdischarge of the control fluid to the control input of the vortex amplifier in response to variations in compressor load when the load exceeds a prescribed load value, and to variations in system capacity when that exceeds a desired, prescribed capacity value.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of one embodiment of the refrigeration system and control of this invention using a solenoid valve and pressure responsive switches;

FIG. 2 is a schematic diagram of another embodiment of this invention showing theuse of a temperature responsive switch in conjunction with a solenoid valve;

FIG. 3 is another embodiment of this invention showing the use of a pilot valve; and

FIG. 4 is a schematic diagram of still anotherembodiment of this invention as used in a system having a subcooling valve as an expansion means. I

against compressor overload and excess system capac- DETAILED DESCRIPTIONS OF PREFERRED EMBODIMENTS In FIG. 1 of the drawing there is shown a refrigeration system of one embodiment of this invention including a compressor means 12, the output of which is connected by a feed line 14, T-connection 16, and feed line 18 to the input of a condenser means 20 for receiving gaseous refrigerant discharged from the compressor means. Condensed refrigerant from the condenser means 20 is fed through a feed line 22 to the input of an expansion device 24 of any suitable type such as a thermostatic expansion valve, capillary tube, subcooling valve, or the like. From the expansion device 24, expanded refrigerant is fed through a feed line 26 to an evaporator 28. The refrigerant in the evaporator 28 is vaporized upon absorption of heat from the medium being cooled. Vaporized refrigerant from the output of the evaporator 28 is fed through a feed line 30, a T connection 32, and a feed line 34 to the main input 40 of a vortex amplifier'42. The vortex amplifier 42 is a fluidic device commonly known in the art and described in the above-referenced US. Pat. No. 3,369,374 and includes, in addition to the main input 40, an output 44, and acontrol input-46. The vortex amplifier 42 is such that the quantity of fluid flow from its main input 40' to its output 44 is a function of the amount of fluid fed to its control input 46. The refrigerant from the output 44 of the amplifier 42 is fed through a feed line 50, a T-connection 52, and a feed line 54 to the input of the compressor means 12.

. The system heretofore described would operate as a conventional refrigeration system for cooling a given medium by contactwith the coils of the evaporator 28.

To provide the control features of this invention a solenoid valve is connected between the T connection 16 and the control input 46 of the amplifier 42 by feed lines 62 and 64. A first pressure sensitive switch is connected by a small conduit 72 to the T-connection 52 located between the amplifier 42 and the compressor means 12. A second pressure sensitive switch 74 is connected by a small conduit 76 to the T-connection 32'located between the evaporator 28 and the amplifier One side of the coil 61 is connected by a conductor.

80 to one side of a suitable source of electrical power. The other side of the coil 61 is connected by a conductor 82 and a conductor 83 to one contact of the switch Operation of the First-Described Embodiment Suppose the capacity of the system is to be controlled when it gets below a prescribed level, and the load on the compressor 12 is to be maintained below a prescribed level. When the evaporator temperature .(which is indicative of system capacity) gets below a prescribed level, the pressure at its output (also indica- 3 tive of system capacity) decreases to below a prescribed value which pressure is sensed by the pressure sensitive switch 74 through the conduit 76. The pressure sensitive switch 74 is designed to close at the prescribed pressure. With the switch 74 closed, power is supplied to the coil 61 to open the solenoid valve 60 allowing an amount of refrigerant to flow from the output of the compressor 12 through the T-connection 16, feed line 62, valve 60, and feed line 64 to the control input 46 of the amplifier 42. The flow ofrefrigerant at the control input 46 reduces the amount of refrigerant flow from the evaporator 28 to the compressor 12 through the amplifier 42 to thereby reduce the capacity of the system and raising the evaporator temperature and output pressure. When its output pressure rises above the prescribed value, the switch 74 opens to close the solenoid valve 60 and again allow full flow of refrigerant from the evaporator 28 to the compressor 12 through the amplifier 42.

The pressure sensitive switch 70 continually monitors the pressure at the input of the compressor 12 through the T-connection 52 and conduit 72. When the pressure at the input of the compressor 12 goes above a prescribed level, indicating an overloadcondition, the switch 70 closes supplying power to the coil 61 toopen the solenoid valve 60. With the valve 60 opened, an amount of refrigerant is fed from the output of the compressor 12 to the control input 46 of the amplifier 42 to restrict, the flow of refrigerant from the evaporator 28 to the compressor 12 thereby reducing the pressure at the input-of the compressor andv preventing its overload. When the pressure at the input of the compressor 12 drops below the prescribed level, the switch 70 opens and the valve 60 closes to cut off the flow of fluid to the control input 46 and allowing full flow of refrigerant from the evaporator to the compressor.

In this manner the system operates between a minimum pressure at the output of the evaporator 28 and a maximum at the input of the compressor 12 to perform the dual function of controlling the-capacity of the system and preventing overload of the compressor.

Although pressure sensors and a solenoid-type valve 100 connected by means ofa conduit 101 to a temperature sensing bulb 102 in an accumulator 103 or other suitable location tosense the temperature of evaporating refrigerant. The accumulator 103 replaces the T- connection 32 of FIG. 1 and is of a type commonly known in the art for'accumulating liquid refrigerant at the output of the evaporatorthatmight otherwise damage the compressor.

The operation of this embodiment is basically the same as that of' the first with the switch being responsive to the temperature of the refrigerant in the accumulator 103' as sensed by the bulb 102, which temperature is a measure of the system's capacity. When the temperature of the refrigerant in the accumulator 103 goes below the prescribed level, the temperature responsive switch 100 closes to open the solenoid valve 60, restricting the flow of refrigerant from the accumulator 103 to the compressor 12 and reducing the capacityof the system. When the temperature goes back up to the prescribed value, the switch 100 opens to allow the system to operate at full capacity. The pressure sensitive switch 70 operatesv as heretofore described to prevent overload of the compressor 12. Of course, a

temperature sensitive switch and appropriate sensor could also be used in place of the pressure sensitive switch 70 and T-connection 52, when it is desirable to reduce the compressor load because of the tempera- In FIG. 3 there is shown another embodiment of the invention wherein the solenoid valve 60 and associated electrical circuit, and the pressuresensitive switches 70 and 74 of the first-described embodiment are replaced with a pilot valve 1 l0 ofa type commonly known in the art. For example, the pilot valve might consist of a single valve which modulates the flow of the refrigerant from the outputof the compressor 12 to the control input 46 of the vortex amplifier 42 in amounts needed temperature sensors.

Theuse of atemperature sensor with the pilot valve 110 is illustrated in the embodiment of FIG. 4. This system differs somewhat from that of FIG. 3 in. that the expansion device 24 is replaced with a subcooling valve 112. The refrigerant from the output of the subcooling valve 112 is fed through a: feed line 114, a liquid cooling coil 116, and a feed line 118 to the input of the evaporator 28. The liquid cooling coil 116 is located in an accumulator 120. Also located in the accumulator 120 is a temperature sensing bulb 122 connected by a conduit 124 to one side of the pilot valve 110. Refrigerant from the evaporator 28 is fed through a feed line 126 to the accumulatorlZo. The accumulator 120 and bulb 122 perform the same functions and operate in the same manner as the accumulator 103 and bulb 102 of the embodiment of FIG. 2. The refrigerant is then fed from the accumulator 120 to the vortex amplifier 42 as with the embodiment of FIG. 2. Thesubcooling valve 112 and liquid cooling coil 116 perform the expansion function, and are of the type commonly known in the art and described in the above-referenced US. Pat. Nos. 3,367,130 and 3,264,837.

The system of FIG. 4 operates with the bulb 122 sensing the temperature'of the refrigerant in the accumulator 120 or in thesaturated portion of the evaporator ture of the refrigerant at the input of the compressor 28. When the temperature gets below a prescribed value, one of the power elements in the pilot valve 110 is operated to modulate the valve opening allowing control refrigerant to pass from the output of the com.- pressor 12 or from the outlet of the condenser when needed and so connected, through the valve 110 to the control input 46 of 'the vortex amplifier 42 restricting the flow of refrigerant from the accumulator 120 to the compressor 12 and reducing the capacity of the system. This continues until the temperature of the refrigerant in the accumulator 120 goes back up to the prescribed value at which time the valve 1 modulates toward the closed position to allow the system to operateat the greatest capacity consistent with the prescribed limits selected. The other power element in the pilot valve 110 operates in the manner heretofore described with respect to the embodiment of FIG. 3 to open the valve 110 in response to pressure sensed at the T-connection 52 in excess of a prescribed value.- Opening the valve 110 restricts the flow of refrigerant from the accumulator 120 to the compressor 112, reducing the pressure at the input of the compressor 112 and preventing its overload. This continues until the pressure of the refrigerant entering the compressor 12 drops below the prescribed upper limit at which time the valve 110 modulates toward the closed position until finally the system is allowed to operate at full capacity.

Hence, there has been described a novel refrigeration system having means performing the dual function of controlling the system capacity and preventing overload of the compressor.

Various changes and modifications may be made in this invention, as will be readily apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

What is claimed is:

1. A refrigeration system comprising a compressor means, a condenser means for condensing refrigerant from the output of the compressor means, an evaporator means for evaporating the refrigerant, an expansion device connected between the output of the condenser means and the input of the evaporator means, a vortex amplifier having a control input and a main input and output, means connecting the output of the evaporator means to the main input of the vortex amplifier, means connecting the output of the vortex amplifier to the input of the compressor means, means for supplying a controlled amount of fluid to the control input of the vortex amplifier when the capacity of the system exceeds a prescribedvalue to restrict the flow of refrigerant from the evaporator means to the compressor means and increase the pressure at the output of the evaporator means to above a selected minimum pressure thereby reducing the capacity of the system, and means for supplying a controlled amount of fluid to the control input of the vortex amplifier when the compressor load exceeds a prescribed value to reduce the pressure at the input of the compressor means to below a selected maximum pressure thereby reducing its load, whereby the system operates between a minimum pressure at the output of the evaporator and a maximum pressure at the input of the compressor to control the capacity of the system and prevent overload of the compressor.

2. The system of claim 1 further comprising a valve means in the flow of control fluid, the valve means being actuatable to allow the control fluid to pass to the control input of the vortex amplifier when the system capacity or compressor load exceeds the prescribed value.

3. The system of claim 2 including means for sensing the capacity of the system between the output of the evaporator means and the vortex amplifier, means for sensing compressor load between the vortex amplifier and the compressor means, the valve means being actuatable in response to the sensing means.

4. The system of claim 3 wherein at least one of the sensing means is temperature responsive.

5. The system of claim 3 wherein at least one of the sensing means is pressure responsive.

6. The system of claim 1 wherein the fluid supplied to the control input of the vortex amplifier is supplied from the refrigerant at the output of the compressor means.

7. The system of claim 1 wherein the expansion device is a subcooling valve, the system further comprising a liquid cooling coilbetween the subcooling valve and the evaporator means through which the refrigerant from the subcooling valve to the evaporator means must flow, and an accumulator between the output of the evaporator means and the vortex amplifier for accumulating liquid refrigerant from the evaporator means, the liquid cooling coil being immersed in the liquid refrigerant within the accumulator. 

1. A refrigeration system comprising a compressor means, a condenser means for condensing refrigerant from the output of the compressor means, an evaporator means for evaporating the refrigerant, an expansion device connected between the output of the condenser means and the input of the evaporator means, a vortex amplifier having a control input and a main input and output, means connecting the output of the evaporator means to the main input of the vortex amplifier, means connecting the output of the vortex amplifier to the input of the compressor means, means for supplying a controlled amount of fluid to the control input of the vortex amplifier when the capacity of the system exceeds a prescribed value to restrict the flow of refrigerant from the evaporator means to the compressor means and increase the pressure at the output of the evaporator means to above a selected minimum pressure thereby reducing the capacity of the system, and means for supplying a controlled amount of fluid to the control input of the vortex amplifier when the compressor load exceeds a prescribed value to reduce the pressure at the input of the compressor means to below a selected maximum pressure thereby reducing its load, whereby the system operates between a minimum pressure at the output of the evaporator and a maximum pressure at the input of the compressor to control the capacity of the system and prevent overload of the compressor.
 2. The system of claim 1 further comprising a valve means in the flow of control fluid, the valve means being actuatable to allow the control fluid to pass to the control input of the vortex amplifier when the system capacity or compressor load exceeds the prescribed value.
 3. The system of claim 2 including means for sensing the capacity of the system between the output of the evaporator means and the vortex amplifier, means for sensing compressor load between the vortex amplifier and the compressor means, the valve means being actuatable in response to the sensing means.
 4. The system of claim 3 wherein at least one of the sensing means is temperature responsive.
 5. The system of claim 3 wherein at least one of the sensing means is pressure responsive.
 6. The system of claim 1 wherein the fluid supplied to the control input of the vortex amplifier is supplied from the refrigerant at the output of the compressor means.
 7. The system of claim 1 wherein the expansion device is a subcooling valve, the system further comprising a liquid cooling coil between the subcooling valve and the evaporator means through which the refrigerant from the subcooling valve to the evaporator means must flow, and an accumulator between the output of the evaporator means and the vortex amplifier for accumulating liquid refrigerant from the evaporator means, the liquid cooling coil being immersed in the liquid refrigerant within the accumulator. 